var prepare_slider = function(x_cols, x_dur){
		
		var x_pos = 0;
		var li_items_n = 0;	
		var li_col = $('slider_list').getElements('li');
	
		li_col.each(function(li, index){
			size = li.getSize();
			x_pos += size.x;
			li_items_n++;
		})
		
		$('slider_list').setStyle('position','relative');
		$('slider_list').setStyle('left','0px');
		$('slider_list').setStyle('width', x_pos+'px');
		/*  alert("The element is "+size.x);  */
		
		var myFx = new Fx.Tween($('slider_list'), {transition: Fx.Transitions.Sine.easeOut, duration:x_dur});
		myFx.addEvent('start', function(){ is_playing = true; });
		myFx.addEvent('complete', function(){ is_playing = false; });
	
		var is_playing = false;

		$('left').addEvent('click', function(){
			cur_offset = $('slider_list').getStyle('left').toInt();
			if (!is_playing && ((cur_offset + size.x) <= 0)) myFx.start('left',   cur_offset + size.x + 'px');
		});

		$('right').addEvent('click', function(){
			var is_playing = false;
			cur_offset = $('slider_list').getStyle('left').toInt();
			if (!is_playing && ((cur_offset - size.x) >= (x_cols*size.x-x_pos) )) myFx.start('left', cur_offset - size.x + 'px'); 
		});	
	}